406FE & Desktop Dyno Cam Results

[blykins]

406ci

4.130" Bore
3.78" Stroke

Iron FE heads with 2.09" intake valves and 1.66" exhaust valves.

10.5:1 CR

750cfm Carb

Edelbrock Performer RPM dual plane intake


I've tried probably 15-20 cams this morning. I've tried Crane, Comp, Crower, and Isky.....solid flat tappets, hydraulic flat tappets, hydraulic rollers, and solid rollers. Actually I've tried everyone that I could find on the webpages. Yes I'm bored. I didn't change the other engine specs....just changed cams so I could find the cam for my wants/needs.

The most horsepower that I can get out of DD2k is 513hp with a mechanical roller cam. Actually I got a couple of 500+ hp cams from my research.

What's really floating my boat though is that I tried several solid flat tappet cams from each manufacturer. There were two that gave me approximately 490 hp. Crane has one that gave me 491hp ...but it's a very wide LSA....so it would probably idle like a Cadillac.

The next cam is a one from Isky. Now get this...

108 LSA, 240 degree duration, but only a .530" lift. Desktop Dyno is showing 491hp at 6500 revs...478 lb-ft at 4500 revs.

Does this make sense for such a low lift?

I'm trying to pick out a cam....and right now I'm doing all the bench racing and researching I can because none of the tech lines are open today. :-)

I really don't think I wanna go with a roller cam. The performance margin that I've found isn't worth the headache and extra $500.

One other thing I've noticed is that when I switch to a single plane intake, the hp goes up considerably. By using that same Isky cam and a single plane intake, the horsepower goes up from 491 to 545hp at the same rpm range. Does this make sense? Is it really that much of a gain? If so, it's definitely worth the price.

Comments are encouraged....I'd like to get all the info I can.

[DAVID GAGNARD]

Blykins;

Normally a single plane intake will make more hp,but also at a higher rpm level,all depends on the total motor package,also single plane intakes usually lose a little hp and torque at lower rpms.........in a light weight Cobra a dual plane intake is all you need unless it is a dedicated race car.............

Also,you should get a better idle with a dual plane intake and they are usually not as tall as a single plane,some cars have a hood clearance problem with a single plane intake...............

Just general terms,I like the dual plane for a street car and use one and a single plane intake on my race car...........

David

[blykins]

David, what are your thoughts on the Isky cam? Do the results seem logical for the specs?

[DAVID GAGNARD]

I'm not real smart when it comes to cams (or much else for that matter ),but different cams have different ramp rates and other variables that make hp at different rpms levels and have different idle characteristics......

I make my decisions based on what I'm going to do with the car....... for my street car I wanted a "hot" driveable motor with good a good idle (had one with way too big a cam and it was a "dog" to drive around),I used a cam with only .484 lift,it was/is a cam with a lot of low end torque,advertised for RV's and towing,makes a lot of power from idle to about 5500 rpms,has a smooth 800 rpm idle,but stand on it and it gets up to 5500 rpms real fast,just right for me and a street car,love it,would not change a thing on this motor.............

For my race car,I'm using a solid roller with almost .600 lift and a lot of duration,idles at 1100 rpms,single plane intake and it makes it's power from about 3000rpms on to about 7000rpms,just right for a non-street legal race car,love that cam for it's intended use............

All depends on what you do with the car and BTW,I really do not worry about hp and dyno numbers that much,what it is,is what it is,as long as I'm happy with the car/motor combo I do not pay much attention to the numbers.......My street car makes only 350 hp (351-W) and I've run and beat many cars at the drag strip with 100 to 150 more hp,you got to get it to the ground to use it and with my set-up,I can put the 350 hp to the ground and use it all when other cars are burning their tires on the starting line!!!!!!!!!!!!!!!

It's nice to have a high hp engine,you gotta be able to use it,I prefer to be able to drive it and enjoy it rather than fight with a "lumpy" idle,overheating motor..........

Just my thoughts..........

David

[blykins]

I'm wanting as much as horsepower as my small block makes....it's 425ci and makes 484hp and 500 lb-ft. I'd like to have that same performance out of an FE.

Also, I like the sound of a revvy motor....but I know I can't get too carried away in that department for obvious reasons. 6000-6500 would probably make me giggle.

The Isky cam I was referring to makes max horsepower (according to DD2k) at 6500.

For some reason, the cam specs didn't jive with me. Shoot my Windsor motor has .544 lift....

[CJ428CJ]

Blykins,

I'm running that very same Isky cam in my 428. 10.25 CR, out of the box Edelbrock heads and the Edelbrock RPM manifold. Prior to this cam, I ran an Isky hydraulic with .565 lift. I like this solid flat tappet cam a lot. I have a noticeable improvement over my prior cam and it idles really well (if you like a nice lumpy idle). I regularly get people asking me what cam I'm running because they like the way it sounds.

Like you, I chose it because of how well Desktop Dyno said it would do in my application. There was one Crane cam and one Comp cam that showed slightly more HP but I liked the 108 lobe seperation on the Isky.

Now, as for actual HP/torque numbers, your guess is as good as mine. I haven't had my motor on a dyno. I might get around to putting the car on a chasis dyno later this summer.

Let me know your email address and I'll send you a spreadsheet with all the cams I Desktop dynoed.

Chris

[blykins]

Chris,

brentlykins@hotmail.com

Thanks....I appreciate the spreadsheet.

So where does your rpm peak? Yours will be a little lower than mine considering I'm running a 3.78" stroke. DD2K shows about 6500 for mine....which is exactly where I need it to be.

Are you running other Isky valvetrain components, or did you stick with Comp or Crane?

[CJ428CJ]

Blykins,

I'm running Isky lifters, the springs that came with the Edelbrock heads and Erson roller rockers. If I remember correctly, my HP peaked somewhere between 5500 and 6000 RPMs. I've included that info on my spreadsheet. I need to get out my laptop and check the spreadsheet. I'll send it to you shortly.

Chris

[blykins]

Chris, I just received the spreadsheet....I'll check it out. Thanks a lot.

So you say this cam sounds good? That's another important aspect to me when choosing a cam.....I like a nice rough radical idle....

[blykins]

Chris, what specs do you use for exhaust when using Desktop Dyno?

I tried to recreate your results...and come up about 15hp shy....I'm using large tube headers with mufflers.

Also, what size carb are you running?

[CJ428CJ]

It's been about a year or more since I ran those numbers through Desktop Dyno . I used large tube headers (I think) but I may have told it open exhaust. I don't recall for sure. For a carb I'm running a 750 cfm. For the Edelbrock heads I was using actual flow numbers for out of the box edelbrocks that I got off the net somewhere. If you're just selecting "wedge heads" or whatever the term is without actual flow data, that may account for the 15 hp difference.

And yes, I love the lumpy idle. That was also one of my primary considerations when I selected this cam too. I'm probably biased, but I've heard a lot of other Cobras and I haven't heard one yet where I said "I wished mine sounded more like that." Heck, if you want to hear it, give me your number. I'll call you and fire it up for ya. Ha, not sure how it might sound over a phone line though but I'd gladly let you listen if you want.

Chris

[blykins]

hehehe....I may have to take you up on that. Nothing more real than hearing it for yourself.

I thought I was using an Edelbrock FE head file....I'll double check the numbers and the flow rates....

Thanks again for all your help Chris. Your spreadsheet was very helpful.

[MidOHasp]

Brent,

IMO, the HP gains shown on DD2K when comparing a single plane to a dual plane are not the most accurate. I am basing this off comparing my dual plane motor (508 HP @ 5800 RPM) to similar motors running single plane intakes (Vic Jr).

To me, it is all about parts matching. I swear by this.... up and down. To me, it is SOOO important.

I threw "smallblock fords for cobra replica convention" to the wind and started with a blank piece of paper.

Ran the Comp Camps XE 282 HR cam:

.565" intake lift
.574" exhaust lift

232* intake duration (@ .050")
240* exhaust duration (@ .050")

RPM Air-Gap intake manifold

AFR 185 cc heads

Speed Demon 750 DP

408 ci

People told me 185cc heads were too small, that the RPM was too small, etc.. etc.. etc......

But on the dyno, it pulled 508HP and 544TQ. Torque curve was flat and very very wide. Over 500 from 3200 to 5400 or something ridiculous.

Had we gone with the 205cc heads, that would have dictated the Vic Jr. Which would have dictated one or two notches up on the cam (closer to 600 lift and 250* duration).

That would have been nice and hairy, but...max power would have been happening at 6800-7000 RPM.

I shift a little past max power (6300) right now and that is great.

I wouldn't want to be pushing 7000 RPM regularly with a 2-bolt 351 block, even though the rotating assembly is good well past 7000.

The engine has seen north of 7000 RPM, accidentally, and it was fine. But those are territories I don't want to chart on a vintage 2-bolt block.

Maybe w/ a Dart or other aftermarket block.

My advice is to not look at one piece individually such as the cam. Decide what kind of engine you want, where you want it making fat torque and peak power, where you want to shift it, and start matching parts together. Don't put a cam that is too big with heads that are too small or vice versa.

I can't tell you how important that advice is...I am a real happy camper having spent a lot of time doing what you are doing right now...bench racing. It did pay off!

[blykins]

JP...that's where I'm trying to head. I know what bore/stroke I have....what heads I will run....what compression, etc.....Just trying to get a cam that will give me the powerband where I want it and try to get more horsepower along the way.

I made a mistake and let Comp Cams tell me what cam to use for my last engine.....They advised I use a cam that makes my engine peter out at 5400 revs with a Vic Jr intake. I figure I'm losing 25-30 hp because of the cam.

So I'm doing a lot of research and I've went through a blue million combos with DD.

[MidOHasp]

It's a good approach, Brent.

I would start by asking some FE experts what you can expect for a reasonable power range on those Iron FE heads. What heads are they?

If you know you are using those heads, I would base everything off of that, unless you are willing to swap heads w/ something else.

If the heads are only good to 5500, then maximize your idle-5500 range with the right intake and cam.

If the heads are good 2000-6000, then go for that.

And so on.

Your heads I would say are the "limiting" factor right now, in that you know you'll be using them. If you didn't have heads, you could tailor it more and do what you want.

Just my 2 cents.

[Bernica]

Brent,

I see lots of great advice already here.

An old and respected FE Master that I knew for years, may he rest in peace, always insisted on no more than 243-245 duration IF the motor was going to run through any kind of mufflers. He also liked a 112* separation under the same conditions.

Also, he would kick my a__ if he heard about me running a single plane manifold on the street.....just not street freindly.

I'm sure to hear objections to these trains of thought.

Good luck.

-Michael